"Don't have nightmares!" Nick Ross used to say, when he hosted Crimewatch, but little did we guess at the Hellraiser-esque horrors haunting our plucky watcher of crime until this weekend. In an extract from his book, Crime, published in the Mail today, Ross reveals that he has been afflicted with a terrible case of visual agnosia which has left him unable to tell the difference between vaginas and laptops.

He writes: "We have come to acknowledge it is foolish to leave laptops on the back seat of a car […] Our forebears might be astonished at how safe women are today given what throughout history would have been regarded as incitement […] Equally they would be baffled that girls are mostly unescorted, stay out late, often get profoundly drunk and sometimes openly kiss, grope or go to bed with one-night stands."

Obviously, writing a manuscript in a state of perpetual confusion between portable computers and female genitals is a distressing condition – is that a return key or a clitoris? – and Ross is to be applauded for battling through to the end of his wordcount. And so, in a spirit of compassion for the baffled, I would like to offer Ross a brief guide to the ways in which women and their vaginas are not like cars and laptops.

1. Not every car contains a vagina

When you carefully tuck your high-value portable property under the passenger seat (just kidding, smash-and-grabbers! That's definitely not where my iPad is!), it's because you don't want potential thieves to know it's there. But draping your vagina in a floor-length modesty frock is unlikely to persuade anyone that don't have one, and therefore might not be worth violating. This is not a quantum mechanics problem. Schrödinger's fanny is not a thing.

2. A laptop is a portable electronic device, a vagina is a body part

Does it whir? Does it make small clicking sounds? Can it be placed in a briefcase and carried around separately to its owner? That is a laptop. Is it a fibromuscular tubular tract located between a woman's thighs? Vagina. Taking the former from a car would be an act of theft. Penetrating the latter without the woman's consent would be a physical assault – and that's true even if the woman has behaved in a way that makes it obvious that she has a vagina and sometimes uses it for fun! No one says to the victim of a beating: "Well, anyone could see you had teeth. You were just asking to have them broken with all the eating you do."

3. You can't insure a vagina

Having your car broken into and your valuables taken sucks. But, understanding that this is a world where some people might be driven to desperate acts for small rewards, you might make a heavy sigh and sweep up the glass (secretly hoping that the drugs your laptop has paid for turn out to be mostly cornflour), and then go and put in your insurance claim. Being raped is – and I know this is going to surprise you, Nick Ross, so prepare yourself – worse than that. There is no insurance that lets you claim back the state of being not-raped. There's no cloud backup to restore your pre-rape internal data. You've been raped, and that is profoundly horrible.

When Ross compares rape to theft, he presents it as a crime of property, not a crime of violence. It's an idea that belongs to the dark ages when women were permitted to own nothing apart from that abstract quality called "honour". Now – oh, fortunate modern females! – we are understood to have to rights to all sorts of things, including the right to decide who we do or don't want in our own orifices. And that's a right we cannot forfeit. Whatever we've drunk, however we're dressed and whoever we've kissed, a vagina is never a laptop.